That's the "battolyser" concept -- store and use the hydrogen from nickel-iron unit charging instead of wasting it. But round-trip storage efficiency is lower v

That's the "battolyser" concept -- store and use the hydrogen from nickel-iron unit charging instead of wasting it. But round-trip storage efficiency is lower via hydrogen (if you want electricity as the end form of energy) and it increases complexity/cost to add systems for hydrogen. So the economics may not be improved even though the energetic efficiency would be.